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Physical location of horn relay on '78 R100/7
- Thread starter SCBuckeye
- Start date
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- Tags
- horn relay
Pretty sure it's under the tank, left side of the backbone. Here's a couple of things to read:
http://forums.bmwmoa.org/showthread.php?41526-Horn-relay
From the Vintage forum, should be able to read the thread:
http://vintagebmw.org/v7/node/9988
http://forums.bmwmoa.org/showthread.php?41526-Horn-relay
From the Vintage forum, should be able to read the thread:
http://vintagebmw.org/v7/node/9988
So, Kent, as far as I know my '78 R100/7 came with dual FIAMM horns installed. Is that not factory? Sure looks like it...most other /7s I've seen have dual horns. Hard to believe that they're all installed after-the-fact without a relay. 
Wouldn't the wiring loom be set up for the relay and could it have been installed? Where on the RS/S models was the relay?? Maybe the OP needs to check the physical location for the presence of a relay.
Wouldn't the wiring loom be set up for the relay and could it have been installed? Where on the RS/S models was the relay?? Maybe the OP needs to check the physical location for the presence of a relay.
Horn relay has a part number of 61 31 1 373 585. You might be able to see those numbers on the relay. The starter relay is 61 31 1 243 207. The horn relay should only have 4 terminals where the starter relay has 5 terminals (a doubled up 87 I believe). Those diagrams are usually on the relay.
jad01
New member
So, Kent, as far as I know my '78 R100/7 came with dual FIAMM horns installed. Is that not factory? Sure looks like it...most other /7s I've seen have dual horns. Hard to believe that they're all installed after-the-fact without a relay.
Wouldn't the wiring loom be set up for the relay and could it have been installed? Where on the RS/S models was the relay?? Maybe the OP needs to check the physical location for the presence of a relay.
I don't know if this is relevant to the R100/7's, but my R80/7 came with a single Fiamm horn and no relay. I purchased and installed an Eastern Beaver relay kit a few years ago (which I like). I bought the kit for dual horns, and just used one line with my single horn. One of these days I'll get around to adding a second horn....
The relay definitely makes a big difference in sound quality.
Max's parts listing shows one for an R100/7
Thanks to all of you. In the next week or so, I will pull the tank and then look. I dreaded the idea of having to pull my WindJammer and getting to the headlight bucket.
My horn recently this past weekend quit working (it had been somewhat intermittent from time to time but finally quit totally on Sunday), so I actually took it off and connected to my car battery, and it about blew my hands off! I then got a used horn off a Honda (guy was parting out and gave it to me). I wired up to my bike, but this time ran the negative side directly to battery instead of trusting the grounding where it was, WOW it worked great . . . until the next morning, and then intermittent until I got near work (about 10 miles) and totally quit. I suspect the relay needs cleaning/replacing.
Thanks again.
My horn recently this past weekend quit working (it had been somewhat intermittent from time to time but finally quit totally on Sunday), so I actually took it off and connected to my car battery, and it about blew my hands off! I then got a used horn off a Honda (guy was parting out and gave it to me). I wired up to my bike, but this time ran the negative side directly to battery instead of trusting the grounding where it was, WOW it worked great . . . until the next morning, and then intermittent until I got near work (about 10 miles) and totally quit. I suspect the relay needs cleaning/replacing.
Thanks again.
Mine must have had dual horns because I remember when purchasing it used about 4 years ago, I remembered that there were two horns (I think they were the FIAMs mentioned by Kurt) but only one was installed, and now I can't even find the loose one.
My system would intermittently work, but after the first "blow" of the horn each day, it would work OK from then on. However, last Sunday, it finally died.
I took off the tank this morning, and found the relay, removed it, and then disassembled it. It was full of crud and corrosion. I cleaned and used 360 wet-or-dry to lightly dress the contacts and prongs.
Now everything works perfectly!!
Thanks to all!!
It didn't happen without pictures!!Did you happen to take any pictures so that someone in the future can compare to their bike?
The location of my horn relay was exactly like the pics above that someone posted. As for pics of my disassembly of the relay, I did not do. But it is pretty easy - because if I can do it, anybody can!
